A fire problem exists in gasoline- and diesel-powered equipment operated in environments in which volumes of organic dusts become aerosolized. The sources of the particles are typically plant residues and there particle sizes are small enough to be suspended in the air. The particles can be deposited and build up on surfaces on the equipment. The equipment is generally equipped with some form of screen to prevent larger airborne residue from reaching the radiator system on the equipment. Small aerosol particles are not, however, trapped by this screen, and it is not practical to filter this volume of air to remove the fine dust. Airborne dust passing through the screen and radiators is then blown by the radiator fan across the surface of the engine. Airborne dust can also enter the engine compartment when winds cause crop dusts from the separator discharge to surround the machine and the dust is entrained.
Engines in agricultural and off-road equipment utilize turbochargers to allow higher power and fueling rates in a compact engine. Trends towards higher specific power levels in engines means high levels of exhaust energy and high temperatures in the components of the exhaust system. Specifically, the exhaust manifold and exhaust turbine reach the highest sustained temperatures external to the engine. Organic dust in the air stream is drawn through the radiators or is entrained into this airstream from dust surrounding the machine and is blown across the exhaust system components including the exhaust manifold and the exhaust turbine. When the engine is heavily loaded and the dust particles are very dry, it is possible for dust deposits on hot surfaces to smolder and/or for some portion of the airborne dust particles passing close to the hottest components to reach auto ignition temperature. These burning particles can be aerosolized or, in the case of airborne particles, remain aerosolized. Subsequently, these particles may be deposited on equipment surfaces that are already coated with combustible residues. Burning particles or embers can then cause smoldering fires to start in a variety of locations on the equipment. When a smoldering residue fire reaches fuel, oil, or synthetic materials, it can spread catastrophically to consume the equipment.